import java.util.Stack;

public class Myqueque_usestacl {
    Stack<Integer> stack1 ;
    Stack<Integer> stack2 ;

    public  Myqueque_usestacl() {
        stack1 = new Stack<>();
        stack2 = new Stack<>();
    }


    public void push(int x) {
        stack1.push(x);

    }

    public int pop() {
        if(stack1.isEmpty() && stack2.empty()) {
            return -1;
        }
        if(stack2.empty()) {
            while (!stack1.empty()) {
                stack2.push(stack1.pop());
            }
        }

        return stack2.pop();

    }

    public int peek() {
        if(empty()) {
            return -1;
        }
        if(stack2.empty()) {
            while (!stack1.empty()) {
                stack2.push(stack1.pop());
            }
        }

        return stack2.peek();

    }

    public boolean empty() {
        return stack1.empty() && stack2.empty();
    }
}
